Na semaforu čekáme, protože auta jedou rychle.

Yes, na often means on, but with places it can also mean at or by, depending on the expression.

So na semaforu is a natural Czech way to say at the traffic light. It does not mean someone is physically sitting on top of the traffic light.

In this sentence, na is used with the locative case, because it describes a location.

• semafor = traffic light
• na semaforu = at the traffic light

Czech often uses prepositions in ways that do not match English word-for-word.

Because after na in the meaning of location, Czech uses the locative case.

The dictionary form is:

• semafor

But after na when talking about being somewhere, it becomes:

• na semaforu

So the ending -u shows that semafor is in the locative singular.

Čekáme is the 1st person plural present tense form of čekat.

• čekat = to wait
• čekáme = we wait / we are waiting

In Czech, the present tense can often translate both:

• we wait
• we are waiting

In this sentence, the natural English meaning is we are waiting.

Because Czech usually does not need a separate verb like English am / is / are when forming the present tense of most verbs.

English:

• we are waiting

Czech:

• čekáme

The meaning we are waiting is already contained in the single verb form čekáme.

Protože means because.

It introduces the reason:

• Na semaforu čekáme = We are waiting at the traffic light
• protože auta jedou rychle = because cars are going/driving fast

So protože connects the main statement with its explanation.

Because protože introduces a subordinate clause, and in Czech that clause is normally separated by a comma.

So:

• Na semaforu čekáme, protože auta jedou rychle.

This comma is standard Czech punctuation.

Yes. Auto is singular:

• auto = car

But here the sentence talks about cars, so it uses the plural:

• auta = cars

In this sentence, auta is the nominative plural, because it is the subject of the verb jedou.

Jedou is the present plural form of jet, which is used for going by vehicle.

• jet = to go / ride / drive by vehicle
• jedou = they are going / driving

Since auta means cars, jedou is exactly the right verb.

Compare:

• auta jedou = cars are driving / moving
• lidé jdou = people are walking

So jet is used because the movement is by vehicle.

This is a very common question.

• jedou comes from jet
• jezdí comes from jezdit

The difference is roughly:

• jet = going on one trip, right now, in a specific direction
• jezdit = going regularly, repeatedly, habitually

So:

• auta jedou rychle = the cars are going fast / are driving fast right now
• auta jezdí rychle = cars drive fast in general / habitually

In this sentence, jedou fits better because it sounds like a current situation at the traffic light.

Because rychle is an adverb, and it modifies the verb jedou.

• rychlý / rychlá / rychlé = fast, quick as an adjective
• rychle = fast, quickly as an adverb

Here we are describing how the cars are moving:

• auta jedou rychle = the cars are going fast

So Czech needs the adverb rychle, not an adjective.

Yes. Czech word order is more flexible than English.

For example, these are both possible:

• Na semaforu čekáme, protože auta jedou rychle.
• Čekáme na semaforu, protože auta jedou rychle.

The first version emphasizes or sets the scene with Na semaforu first: At the traffic light, we’re waiting...

The second sounds a bit more neutral: We’re waiting at the traffic light...

Both are correct.

No. It means we are waiting at the traffic light, not waiting for the traffic light as an object.

If you wanted to say waiting for something in Czech, you usually need na with the accusative after čekat:

• čekáme na autobus = we are waiting for the bus

But here na semaforu is not the object of čekáme. It is a location phrase meaning at the traffic light.

So the structure is:

• Na semaforu = at the traffic light
• čekáme = we are waiting

Usually yes. Semafor is the normal Czech word for a traffic light or signal.

Depending on context, it can refer to:

• a traffic light for cars
• a pedestrian crossing light
• a signal light more generally

In this sentence, the natural meaning is the ordinary road traffic light.